Document Type : Original Article
Authors
1 Tobacco Prevention and Control Research Center (TPCRC), National Research Institute of Tuberculosis and Lung Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran
2 Reproductive Biotechnology Research Center, Avicenna Research Institute, ACECR, Tehran, Iran
3 National Research Institute of Tuberculosis and Lung Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran
Abstract
Keywords
Despite the efforts made in order to control tobacco
consumption across the world, smoking is still common
(
Cigarette smoke contains known mutagenic
and carcinogenic substances, and is believed to
have a significant negative effect on male fertility
(
Cigarette smoking has negative effects on male
fertility. Recent studies have shown the active
transfer of several components of cigarette smoke
through the blood-testis barrier (
Smoking is associated with a small reduction
in semen quality including sperm concentration,
motility and morphology. It is also associated
with alterations in hormone levels in males. for
example, it increases the levels of oestrone and
oestradiol.Male smokers with estron quality who
wish to have children may benefit from quitting
smoking (
Some studies have reported the negative effect of
smoking on sperm concentration (
For example, in an Australian prospective study,
the semen parameters and hormone concentrations
of infertile smokers were compared with those
of infertile non- and ex-smokers (men who had
stopped smoking more than six months prior to
the study). They studied 517 non-smokers, 109 exsmokers
and 478 smokers, and found that smoking
does not affect the conventional semen parameters,
result of the study showed significantly increase of
round and leukocytes (
The result of a study of semen quality was conducted
on 197 smoker and 161 non-smoker Mexican
males, undergoing initial infertility investigation,
compared with non-smokers, smokers had
significantly poorer sperm density, a lower percentage
of viability, a lower percentage of sperms
with normal morphology, and a lower percentage
of motile sperms. These parameters were worse in
the heavy smoker groups (
In another study, the semen quality of two groups
of Italian men with idiopathic infertility (118
smokers and 153 nonsmokers) was compared. The
infertile smoker and non-smoker patients showed
similar sperm parameters. Although morphology
evaluated by the transmission electron microscopy
(TEM) analysis in both groups were significantly
impaired compared with the controls, however
sperm concentration and fertility index in the
heavy smokers were significantly lower than those
observed in the mild smoker and non-smoker
groups (
This study was designed to evaluate the effect of smoking on concentration, motility and morphology of sperms in Iranian infertile couples.
In this cross-sectional study performed from November 2008 to March 2009 at the Avicenna Infertility Clinic(Tehran, Iran),180 married men with one year history of idiopathic infertility who were able to produce semen, were randomly selected to participate in the study . This survey was approved by the Ethics Committee of National Research Institute of Tuberculosis and Lung Diseases (NRITLD) and the patients satisfaction was documented.
Cases with a history of cryptorchidism, orchitis, varicocele, inguinal hernia, testicular trauma, vasectomy, systemic or urogenital diseases, exposure to a specific substance or drug consumption were excluded from the study.
Smoking history was evaluated through a standard questionnaire containing questions on smoking status, number of cigarettes smoked per day, years of smoking, nicotine dependence and wife’s smoking status.
Patients with a history of smoking were considered smokers and those with no history of smoking were considered nonsmokers. Based on the World Health Organization (WHO) standards, if one had smoked 100 cigarettes in his life time, he was considered an active smoker (if a participant smoked at least one cigarette per day, he was considered as daily smoker, if he smoked occasionally during last year, he was categorized as occasional smoker and if one had smoked 100 cigarettes in his life time, but quitted and was a non-smoker at the time of study, he was considered as an ex-smoker).
Nicotine dependence was evaluated using the
Fagerstrom’s test, which contains 6 questions with
a score of 0 -10, and based on their score, the smokers
were grouped into mild (score,0-3), moderate
(
The semen samples were collected based on the
WHO standards after 3-6 days of abstinence (
Microscopic examination and evaluations of the pH, volume, viscosity, appearance, concentration, motility, agglutination, and morphology analysis of sperms were all performed.
The results obtained were evaluated based on theWHO criteria as follow:
Semen volume -(ml): minimum of 1.5 ml
Sperm concentration – (sperm per ml): minimum of 15 million/ml
Total motility: minimum of 40%
Morphology (normal forms): minimum of 4%.
Descriptive analyses were performed using the SPSS software, version 16. T test and Mann - Withney tests with a significance level of α=0.05 were also used for statistical analysis. Kolmogorov Smirnov’s test, normal curves and histograms were used to determine distribution normality. If distribution was not normal, Mann - Withney test was employed. Using t test, the variables were placed into groups of smoker and nonsmoker and also active smoker, and the remaining group (the remaining group contained occasional smokers plus nonsmokers. Ethical issues like privacy of information were followed in this study and an informed consent was obtained from all the participants.
One hundred and eighty individuals presenting to the Avicenna Infertility Center participated in this study.The cases were in the age range of 22 to 68 years with a mean age of 35.26 ± 6.63 years. A total of 56 (31.3%) participants had high school diploma and 46 (25.6%) had collage education or Bachelor’s degree. A total of 69 subjects (38.3%) were employers, 47 (26.1%) were employees , 41(22.7%) were workers and 23(12.7%) had other occupations. Duration of treatment for infertility ranged from 1 month to 25 years with a mean of 4.86 ± 5.4 years.
Also 68 (37.8%) subjects were nonsmokers
and 112 (62.2%) were smokers among them71
(39.4%) subjects were active smokers. Of these 71
cases, 21 (11.7%) had quitted smoking by the time
of conduction of this study and the remaining 50
(27.8%) continued to smoke actively. Of the latter,
14 (7.8%) smoked occasionally and 36 (20%)
smoked daily (
Sperm morphology results showed that 168
individuals (93.3%) were teratozoospermic.
Sperm motility evaluation revealed that 60
individuals (33.3%) were astenozoospermic
(
Distribution of active smoking status (number of cigarettes per day early morning smoking and nicotine dependence) among the infertile married men presenting to the Avicenna Infertility Center
Active smoking | Number | Percentage | |
---|---|---|---|
Less than 10 cigarettes | 31 | 64.6% | |
10-30 cigarettes | 6 | 12.5 | |
More than 30 cigarettes | 11 | 22.9 | |
Total | 48 | 100 | |
In the first 5 minutes | 4 | 8.3 | |
In 6-60 minutes after waking up | 5 | 10.4 | |
One hour after waking up | 39 | 81.3 | |
Total | 48 | 100 | |
Mild dependence | 31 | 64.6 | |
Moderate dependence | 10 | 20.8 | |
Severe dependence | 7 | 14.6 | |
Total | 48 | 100 | |
Distribution of the sperm analysis parameters (minimum, maximum, mean) among the infertile married men presenting to the Avicenna Infertility Center
Semen analysis | Minimum | Maximum | Mean |
---|---|---|---|
10 | 580×106 | 84 × 106 ± 78 × 106 | |
0% | 42% | 11.35% ± 8.22% | |
0% | 80% | 49.97% ± 17.49% | |
Distribution of the mean sperm characteristic based on the smoking status among the infertile married men presenting to the Avicenna Infertility Center
Semen analysis | Sperm concentration | Morphology | Motility |
---|---|---|---|
102×106 ± 100×106 | 10.39 ± 8.09 | 49.55 ± 15.17 | |
73×106 ± 58×106 | 11.94 ± 8.27 | 50.22 ± 18.82 | |
0.03 | 0.21 | 0.4 | |
94×106 ± 90×106 | 10.76 ± 8.24 | 49.85 ± 16.64 | |
68×106 ± 51×106 | 12.28 ± 8.16 | 50.15 ± 18.83 | |
0.04 | 0.24 | 0.64 | |
Sperm analysis abnormalities were more common
in the smokers and active smokers compared
to the non-smokers. T test and chi square put:
Mann-whitney tests were used to compare sperm
concentration, morphology and motility based on
the smoking status. The mean sperm concentration
was 102×106 ± 100×106 in the nonsmokers and 73,
×106 ± 58×106 in the smokers, which was significantly
lower in smokers (p=0.03). No significant
difference was found between the smoking status
and the sperm morphology or motility (
T test and Mann - Whitney tests were done among
the active smokers and the remaining group (nonsmokers
plus occasional smokers). The mean sperm
concentration of semen was 94×106 ± 90×106 and
68×106 ± 51×106 in the above mentioned groups,
respectively and was statistically lower among the
active smokers (p=0.04). However, no significant
difference was observed in other semen characteristics
(morphology and motility) between the two
groups (
Despite the harmful effects of smoking on humans
health and being among the most important
causes of morbidity and mortality worldwide,
still 1/3 of the world population above 15 years
of age smoke daily (
In this study, 20% of the infertile men smoked daily, 7.8% smoked occasionally and 11.7% were ex-smokers in comparison to the public statistics of 22% daily smokers, 2.5% occasional smokers and 12.3% ex-smokers. In contrast to the assumption that infertile men smoke less, statistics showed that their smoking rate was not significantly different from the general public. Further studies are required to determine whether smoking is a risk factor for infertility and decreased response to treatment.
Many studies have proposed a correlation
between smoking and changes in semen quality
but various results have been obtained. Important
variables affected sperm concentration,
morphology and motility (
In some studies, decreased sperm concentration
has reported to be in relation with smoking
(
In our study on Iranian male population, sperm concentration of the smokers was significantly lower than nonsmokers. This finding is in accordance with those of some other studies propounding the probability of racial or genetical susceptibility to nicotine: the fact is that in some nationalities, nicotine can influence sperm parameters more effectively. Also in the present study, a significant sperm concentration difference was found between the active smokers and the remaining group indicating the negative effect of even small amounts of tobacco consumption. Further studies are recommended on this subject.
Similarly, various results have been found regarding
the changes in sperm morphology based
on smoking status (
In the present study, most of the active smokers had mild nicotine dependence and smoked less than 10 cigarettes per day. However, there was a small correlation between the two factors, which suggesting that infertile smokers are trying to cut down smoking, or under-report their consumption.
As mentioned earlier, most of our study population were university graduates. This rate is higher than the educational level of Iranian general population. Therefore according this research, it seems that some factors related to educational level can impact the increased risk of male infertility, which should be further evaluated in an especially designed survey.
Smoking even in small amounts like one-time smoking per day may decrease the sperm concentration. Therefore, smoking cessation programs are recommended at least for the infertile patients. Other study with long-term fallow-up may clear the contradictory results observed in the literature.
This study did not support an overall correlation between sperm analysis and smoking status. But sperm concentration was significantly decreased in active smokers and even in those consuming small amounts of tobacco product. So it suggest that tobacco consumption may negatively affect fertility.